ABSTRACT
CATT/Trypanosoma brucei (T.b.) gambiense is an antibody detection test currently used in field surveys on Gambian sleeping sickness. The screening test is usually performed on a drop of freshly collected heparinized blood, followed by a more specific confirmation test on diluted blood, plasma or serum. This approach may be biased by the occurrence of a complement-mediated prozone phenomenon causing lower test sensitivity at lower sample dilutions. A simple remedy is by addition of a Ca2+ chelating agent such as EDTA.
Subject(s)
Agglutination Tests , Complement Activation/immunology , Trypanosoma brucei gambiense/immunology , Trypanosomiasis, African/diagnosis , Africa, Western , Animals , Antibodies, Protozoan/blood , Antigens, Protozoan , Humans , Mass Screening , RabbitsABSTRACT
Le depistage systematique de la maladie du sommeil a Trypanosoma brucei gambiense dans un foyer endemique necessite la mise en oeuvre de tests serologiques detectant des anticorps specifiques. A cet egard; certains tests d'agglutination relativement simples ont l'avantage de donner une reponse rapide sur le lieu de rencensement meme
Subject(s)
Trypanosoma brucei gambiense , Trypanosomiasis , Trypanosomiasis/diagnosisABSTRACT
A rabbit polyclonal serum was raised against the 29-kDa species-specific marker, as well as the 30- to 34-kDa immunotype-specific markers of Haemophilus ducreyi described elsewhere (E. Roggen, S. De Breucker, E. Van Dyck, and P. Piot, Infect. Immun. 60:590-595, 1992). These antigens were purified from a cocktail of H. ducreyi isolates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The immune serum reacted in enzyme-linked immunosorbent assay (ELISA) preferentially with H. ducreyi, at a titer as high as 50,000. To make it specific to H. ducreyi, nonspecific antibodies were removed by adsorption on a mixture of Haemophilus spp., Escherichia coli, Candida albicans, and Corynebacterium spp. In the 29- to 34-kDa region of immunoblot profiles from H. ducreyi isolates (n = 450), the adsorbed serum revealed essentially the same antigens as did a pool of well-characterized human sera. Yet, eight different immunotypes were observed. With this rabbit polyclonal serum, an ELISA-based antigen detection test was developed. The adsorbed serum reacted specifically with all H. ducreyi isolates tested (n = 450), but not with other bacterial species (n = 15). This test was evaluated with a limited number of clinical specimens from African patients with culture-proven chancroid and no evidence for any other ulcerating etiology (n = 10) and a number of chancroid-negative control patients from Belgium (n = 20). Within this context, the test yielded a sensitivity and specificity of 100%.
